Coaxial transmission line



Oct. 26, 1943. H. E. REPPERT COAXIAL TRANSMISSION LINE 5' Sheets-Sheet 1 Filed Oct. l. 1940 uwlnron Hugh E. Bepper BY Arromvs y ,Oct 26, 1943. Y H. E. Rr-:PPERT l 2,332,529

COAXIAL TRANSMISSION LINE l I Filed oct. 1. 1940 u s sheets-sheet 2 INVENTOR Hugh E. liepperl BY e i TTCRNEY Oei. 26, 1943. H. E. REPPERT COAXIAL TRANSMISSION LINE Filed Oct. 1 1940 5 Sheets-Sheet 3 :E l E.; 4

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Patented Oct. 26, 1943 COAXIAL TRANSMISSION LINE Hugh E. Reppert, San Diego, Calif.

Application October 1, 1940, Serial No. 359,228

(Granted under the act of March 3, 1883, as

amended April 30, 1928; 370 O. G. 757) 14 Claims.

My invention relates to a coaxial transmission line and more particularly to a. sectionalized transmission line of the stated character.

's is well known, coaxial transmission lines are employed for transmitting radio frequency energy because of the many structural and elecv:trial advantages inherent therein. Among the .advantages possessed by coaxial transmission :lines are the maintenance by the same of substantially uniform electrical characteristics un- 4tier all service conditions and the ability to increase the power transmission thereof by the introduction of gas under pressure between the outer and inner concentric conductors.

Where it becomes necessary to employ a sectionalized coaxial transmission line it is essential to retain the above enumerated advantages even where the sectionsv for any reason must be relatively movable. The foregoing desirable result is achieved by the present invention through the provision of a sectionalized coaxial transmission line in which the sections are relatively movable and sealed one to the other while main: taining electrical continuity therebetween.

In the preferred embodiment of the present. invention the sectionalized coaxial transmission line is comprised of a plurality of relatively moving the desired fluid-tight relation between the relatively movable sleeves.

In the light of the foregoing, it is among the principal objects of my invention to provide a sealed sectionalized coaxial transmission line in which the sections are relatively movable and electrically continuous; to provide a transmission line of the stated character in which the electrical line of the stated character in which the electrical connections between the sections and other in- `terior parts of the latter are sealed against acable sections, one of which includes a pair of insulatingly spaced concentric cond-uctors and another of which includes a pair of insulatingly spaced concentric conductors electrically continuous with the first mentioned pair.l Means is provided for sealing one transmission line section to another, the said means including a pair of concentric relatively movable sleeves secured to the outer conductors ofthe respective conductor pairs and held in rotative fluid-tight relation.

While in the preferred embodiment of the present invention gas is maintained under pressure between the outer and inner concentric conductors of the transmission line sections and is prevented from escaping by the sealing means, it is within the purview of the present invention to employ instead a dry gas at atmospheric pressure. In the latter case the sealing means prevents the ingress of extraneous moisture or other uids that would tend to alter the electrical characteristics of the transmission line and for this purpose includes a resilient convoluted member associated with the sleeves to assist in maintaining a fluid-tight relation therebetween. Where the gas is under pressure, however, the resilient member is preferably retained but is not essential since the pressure of the conned gas alone may be employed to assist in maintaincess of extraneous fluids; and to provide a transmission line of the character above noted emplcying gas under pressure in which the pressure of the confined gas assists in maintaining a uidtight seal between the sections thereof.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection .with the accompanying sheets of drawings, wherein:

Fig. l is a central longitudinal sectional view ofone embodiment of the sectionalized transmissi line of the present invention in which the sections thereof are sealed one to the other by relatively movable sleeves in fluid-tight engagement at their conical bearing surfaces; s.

Fig. 2 is bottom plan view of the sectionalized transmission line of Fig. l slggwing, among other things; the construction of Tone onthe spacing insulators;

Fig. 3 shows the sectionalized transmission line of Fig. 1 as used with a directive loop antenna.

Fig. 4 is a central longitudinal-sectional view of a still further embodiment of the sectionalized transmission line of the present invention wherein a exible flanged cylindrical member is Aemployed for effecting a seal between the relatively movable sleeves; and

Fig. 5 is a perspective view of the flanged cylindrical sealing member employed in the embodiment of Fig. 4.

Turning now to the drawings, there is shown in Figs. 1 and 2 thereof a sectionalized coaxial transmission line comprised of a plurality of relatively movable sections, one of which includes a pair of insulatngly spaced concentric electrical conductors I and 2 and another of which includes a pair of insulatingly spaced concentric electrical conductors 3 and 4 electrically continuous with the first mentioned pair. Insulators 5 fabricated of any suitable material are employed to maintain the inner conductors 2 and 4 spaced and electrically insulated from the outer concentric conductors I and 3, the insulators being shown by way of example as peripherally serrated to pemit the passage of gas along and between the transmission line sections as clearly indicated in Fig. 2.

The inner conductors 2 and 4 and the outer conductors I and 3 of the respective sections are electrically and detachably connected in any suitable manner. Thus, the inner conductor 2 is shown by way of illustrationas provided with an integral male contact member 6 slidably engaging the walls of a recessed female contact member 1 integral with the inner conductor 4 in a manner to establish electrical continuity between these conductors in all rotative positions of adjustment of the transmission line sections.

One of the pair of relatively movable sleeves is conveniently, although not necessarily, employed for electrically interconnecting the outer conductors I and 3 of the respective sections. Thus, as clearly shown in the drawings, the inner sleeve 8 is fabricated of some suitable electrically conductive material and is secured to the outer conductor 3 in a fluid-tight and electrically continuous manner. The sleeve 8 is provided with a cylindrical extension 9 that serves asa female contact member and receives in sliding engagement therewith the slotted terminal portion I0 of the outer conductor I. The terminal portion I serves as a male contact member which by virtue of its resilient slotted construction and its tight iit is maintained in intimate electrical contact with the inner wall surface of the cylindrical extension 9 in all rotative positions of adjustment of the transmission line sections.

For sealing one transmission line section to the other, there is provided a pair of relatively movable sleeves 8 and I I secured to the outer conductors 3 and I of the respective conductor pairs and having complementary conical bearing surfaces I2 and I3 respectively. A flange l4 is affixed to the outer conductor I in a fluid-tight manner and has detachably secured and sealed thereto the outer sleeve I I by means of the screws I and the intervening gasket IS.- Where the transmission line section comprised 'of the conductors I and 2 is to be movable the flange I4 may be provided with the cylindrical member I1 secured thereto by the screws I8 for facilitating the rotation of the same. By detachably connecting the outer sleeve I I and flange I4 it is possible to disconnect and disassemble the transmission line sections when this becomes necessary or is desired.

To assist in maintaining an effective fluid-tight seal at the complementary conical bearing surfaces I2 and I3 of the sleeves and to reduce to a minimum any friction between the relatively movable surfaces of the sleeves 3 and II, the inner sleeve 8 is provided with a series of annular grooves I9 for receiving a suitable lubricant of proper viscosity which may be conveniently chosen as a heavy oil. The grooves I9 are machined sufficiently deep so that they may initially receive a quantity of lubricant to provide a reserve supply thereof. The lubricant spreads in a thin film between the juxtaposed surfaces of the sleeves 8 and II and not only reduces the rotational frictional losses to a minimum but also assists in maintaining an effective duid-tight seal at the conical bearing surfaces I2 and I3.

When using a dry inert gas at atmospheric pressure between the outer conductors I and 3 and the inner concentric conductors 2 and 4 of the transmission line sections, a convoluted resilient member 20 of the compressional type is employed for maintaining the conical bearing surfaces I2 and I3 of the sleeves in wedging but rotative ,fluid-tight engagement. The compression spring 20 has secured thereto in any suitable manner the bearing rings 2| and 22 which engage complementary bearing surfaces 23 and 24 on the flange I4 and on the terminal portion of the sleeve 8 respectively. By disposing the spring 20 in the manner depicted in the drawings, the sleeves 8 and II are urged in opposite directions to maintain the complementary conical bearing surfaces I2 and I3 of the sleeves 8 and II respectively in juxtaposed relation and thus effect a seal between the transmission line sections.

Where a dry inert gas above atmospheric pressure, as nitrogen for example, is disposed between the outer conductors I and 3 and the inner concentric conductors 2 and 4, as in the embodiment depicted in Fig. 1, the compression spring 20 may be dispensed with if desired, since the sleeves l and II will be urged in opposite directions to maintain the conical bearing surfaces I2 and i3 f in wedging but rotative fluid-tight engagement by the pressure of the confined gas alone. This follows from the fact that the gas pressure within the spring chamber 25 is substantially identical with that obtaining between the outer conductors I and 3 and the inner conductors 2 and 4 of the transmission line sections because of the gas leakage between the outer contact members 9 and I0. While in most cases the pressure of the gas within the transmission line sections will be sufficiently in excess of that of the circumamblent atmosphere to alone maintain an effective fluid-tight seal at the conical bearing surfaces I2 and I3 of the sleeves, it is preferred to retain the spring 20 so that the seal at the conical bearing surfaces I2 and I3 may not be broken if for any reason the gas pressure within the transmission line should be disturbed.

Fig. 3 shows the sectionalized transmission line of Fig. l as used with a directive loop antenna. The cylindrical member I1 for facilitating rotation of the upper transmission line section connected to the loop antenna 26 is rotatably supported from the stationary base 21 in any suitable manner. The handwheel 28 secured to the cylindrical member I1 provides a ready means for lmparting the desired rotation to the antenna. The lower stationary transmission line section has an electrical terminal 29 secured to the outer conductor 3 in a gas-tight and'electrically continuous manner, the inner concentric conductor of this section being provided with the electrical terminal 30. The terminals 29 and 30 are electrically insulated from each other by sleeve 3| of any suitable insulating material the sleeve being sealed in a gas-tight manner to both of the terminals.` lBy means of the terminals 29 and 33 it thus becomes possible to either transmit or receive electrical energy to or from the directive antenna 26. A self-closing valve 32 of any known prior art construction provides a means for filling all sections of the transmission line with a gas or mixture of gases at any desired pressure, the

pressure being indicated by any suitable gauge 33.`

Turning now to Figs. 4 and 5 of the drawings there is shown a still further embodiment of the sectionalized coaxial transmission line of the present invention likewise comprised of a plurality of relatively movable sections, one of which includes a pair of insulatingly spaced concentric electrical conductors 34 and 35 and another o! which includes a pair of insulatingly'spaced concentric electrical conductors 36 and 31 electrii Y I, l

cally continuous with the first mentioned pair. Insulators 36 fabricated of any suitable material are employed for maintaining the inner conductors 35 and 31 spaced and electrically insulated from the outer conductors 34 and 36, the insulators 38 being provided with irregular peripheral portions to permit the passage of gas along and between the transmission line sections.

The inner conductors 35 and 31 and the outer conductors 34 and 36 of the respective sections are electrically and detachabiy connected in any suitable manner as in the previous embodiment. Thus the inner conductor 35 is shown by way of example as provided with a male contact member 39 electrically continuous therewith and slidably engaging the walls of a recessed female contact member 40 likewise electrically continuous with the inner conductor 31 in a manner to establish electrical continuity between the conductors 35 and 31 in all rotative positions of adjustment of the transmission line sections.

One of `the pair of relatively movable sleeves may again be conveniently employed for electrically interconnecting the outer conductors 34 and 36 of the respective transmission line sections. As clearly indicated in the drawings the inner sleeve 4| fabricated of some suitable electrically conductive inaterial is secured at one of its ends to the outer conductor 34 in a fluid-tight and electrically continuous manner. At its remaining end the sleeve 4|` is provided with a cylindrical slotted extension 42 that serves as the female An annular-,pad 44 of any suitable material iml pregnated with a proper lubricant may be optionally employed to reduce the friction between the outer contact members 42 and 43.

For sealing one transmission line section to the other there is provided, among other things, a pair of relatively movable sleeves 4| and 45 secured to the outer conductors 34 and 36 of the re.

spective conductor pairs and having complemenl tary bearing surfaces 46 and 41 respectively. n Between the bearing surfaces 46 and 41 there is interposed for cooperation therewith a well lubricated thrust bearing comprised of the ball bearings48 and the annular thrust plates 49 and 50 to take up the thrust exerted by the sleeve 4| against the sleeve while permitting free rotative movement therebetween. y

A flange 5| is affixed to the outer conductor 36 in a fluid-tight manner and has detachabiy secured and sealed thereto the outer sleeve 45 by means of the screws 52 and the intervening gasket 53. Where the transmission line section .1 comprised of the conductors 36 and 31 is to be movable the flange 5| lmay be providedwith the 45 is provided with a lubricated packing 51 that is maintained in position by the gland 58 adjustable by the nut 59 in threaded engagement with the sleeve 45. The lubricated packing 51 insures the provision of a thin film of lubricant between the juxtaposed sleeve surfaces so that one sleeve may at all times rotate freely with respect to the other sleeve.

For sealing one sleeve to the other afianged cylindrical member identified in general by the reference character 60 (Fig. 5) is provided and disposed intermediate the sleeves 4| and 45 as clearly indicated in Fig. 4." The member 60 is fabricated of any suitable fluid impervious material which may for example be fibrous or metallic in character; and the cylindrical wall 6| thereof is rendered flexible in any suitable manner as by tapering the wall thickness thereof to a thin edge as indicated in the drawings. The flange 62 of the cylindrical member 60 is in fluid-tight engagement with the terminal surface 63 of the inner sleeve 4| while the flexible cylindrical wall 6| thereof, by reason of its close llt and resilience, is in fluid-tight engagement with the inner wall surface 64 of the outer sleeve 45. The flange 62 of the cylindrical member 60 may, if desired, be cemented or otherwise secured to the terminal surface 63 of the sleeve 4| to thus rotate with the sleeve and further enhance the fluid-tight seal subsisting therebetween.

When employing a dry inert gas at atmospheric pressure between the outer conductors 34 and 36 and the inner conductors 35 and 31 of the transmission line sections, a convoluted resilient member 65 of the compression type isV employed for insuring the maintenance of the flange 62 of the cylindrical member 6D in fluidtight engagement with the terminal surface 63 of the sleeve 4|, the thrust exerted by the compression spring 65 being taken up by the thrust bearing previously described herein. The compression spring 65 has secured thereto in any suitable manner the bearing rings 66 and 61 which engage respectively a complementary bearing surface 68 (Fig. 5) on the flange 62 integral with the cylindricalmember 6D and the complementary bearing surface 69 on the flange 5| affixed to the outer conductor 36.

Where dry inert gas above atmospheric pressure is disposed between the outer conductors 34 and 36 and the inner concentric conductors 35 and 31 of the transmission line sections as in the embodiment depicted in Fig. 4, the compression spring 65 may be dispensedl with ii desired, since the flange 62 and flexible cylindrical wall 6I of the member 60 will be maintained in fluidtight engagement with the respective surfaces 63 and 64 of the inner and outer sleeves 4| and 45 by the pressure of the confined gas alone, the seal between the `cylindrical wall 6| and its cooperating surface 64 being thereby enhanced. This follows from the fact that the gas pressure Within the spring chamber 10 is substantially identical with that obtaining between the outer conductors 34 and 36 and the inner conductors 35 and 31 of the transmission line sections because of the gas leakage between the outer contact members 42 and 43. It is this gas pressure within the 'spring chamber 10 that exerts a flexing action on the cylindrical wall 6| of the member 6|| and a thrusting action 0n`the flange 62 thereof that is taken up by the thrust bearing, which together effect and insure a fluid-tight seal between the flanged cylindrical member 60 and the relatively movable sleeves 4| and 45. While in most cases the pressure of the gas within the transmission line sections will be sufficiently in excess of that of the circuinambient atmosphere to alone maintain an effective fluid-tight seal as described, it is preferred to retain the compression springs 65 so that the sealbetween the flange 62 of the cylindrical member 60 and the terminal surface 63 of the sleeve 4| may not be broken il for any reason the gas pressure within the transmission line should be disturbed.

From the foregoing it should be clear that the means depicted in Figs. 1 and 4 for sealing one transmission line section to another prevents the escape of any gas under pressure. If, on the other hand. dry gas at atmospheric pressure is employed between the outer and inner concentric conductors of the transmission line sections, the sealing means prevents the ingress of extraneous moisture or other fluids that would tend to alter the electrical characteristics of the transmission line. In this connection, it should be observed that the inner and outer contact members electrically -interconnecting the transmission line sections are fully protected against access of extraneousfluids that might tend to impair the low resistance contact therebetween.

According to the provisions of the'patent statutes, I have set forth the principleand mode of operation of my invention and have illustrated and described what I now consider to represent its best embodiments. have it understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically illustrated and described.

The invention herein described and claimed may be used and manufactured by or for the Government of the United States of America for latingly spaced from the first mentioned pair of conductors, a pair of relatively rotatable sleeves, l

one of said sleeves being secured to one of said outer conductors, the other of said sleeves being secured to the other of said outer conductors in concentric relation and interior engagement with the first mentioned sleeve, the second mentioned sleeve extending from the outer conductor secured thereto to slidably engage the juxtaposed end of the remaining outer conductor within the confines of the first mentioned sleeve to establish electrical continuity therebetween.

3. A sectionalized coaxial transmission line comprising in combination a first pair of insulatingly spaced concentric conductors, a second pair of insulatingly spaced concentric conductors arrangedfor connection with said first mentioned pair, means for establishing electrical connec- However, I desire to governmental purposes without the payment of any royalties thereon or therefor.

I claim:

l. A sectionalized coaxial transmission line comprising in combination a pair of inner relatively movable electrically connected conductors, a pair of outer relatively movable electrically connected conductors concentric with and insulatingly spaced from the .first mentioned pair of conductors, a gas under piessure between the inner and outer conductor pairs, a pair of relatively movable sleeves provided with complementary bearing surfaces, one of said sleeves being secured to one of said outer conductors, the other of said sleeves being secured to the other of said outer conductors in concentric relation and interior engagement with the first mentioned sleeve, the second mentioned sleeve extending from the outer conductor secured thereto to slidably engage the juxtaposed end of the remaining outer conductor for establishing electrical continuity therebetween and the sleeves being associated in a fluid-tight manner to prevent the escape of the aforesaid gas, a convoluted resilient member associated with said sleeves, the said member and the pressure of the aforementioned gas being operative to maintain complementary bearing surfaces of the sleeves in juxtaposed relation.

2. A sectionalized coaxial transmission line comprising in combination a pair of inner relatively rotatable electricailyconnected conductors, a pair of outer relatively rotatable electrically connected conductors concentric with and insutions between the inner and outer conductors of the respective conductor pairs and means for sealing the electrical connections against access of extraneous fluids, the said pairs of conductors being relatively rotatable.

4. A sectionalized coaxial transmission line comprising in combination a plurality of relatively 'rotatable sections, one of said sections including a pair of insulatingly spaced concentric conductors, another of said sections including a pair of insulatingly spaced concentric conductors arranged for connection with said rst .mentioned pair, means including relatively movable parts for establishing electrical connections between the inner and outer conductors of the respective conductor pairs, and means for sealing the electrical connections against access of ex. traneous fluids, said last mentioned means in cluding a pair of concentric relatively rotatable sleeves secured to the outer conductors of the respectiveconductor pairs.

5. A sectionalized coaxial transmission line comprising in combination a plurality of relatively movable sections, one of said sections including a pair of insulatingly spaced concentric conductors, another of said sections including a pair of insulatingly spaced concentric conductors arranged for connection with said first mentioned pair, means including relatively movable parts for establishing electrical connections between the inner and outer conductors of the respective conductor pairs, a pair of concentric relativelyv movable sleevessecured to the outer conductors of the respective conductor pairs, and a convolut ed resilient member disposed intermediate said sleeves. the said member being operative t .maintain complementary bearing surfaces sleeves in juxtaposed relation.

6. A sectionalized coaxial transmission line comprising in combination a plurality of relatively movable sections, one of said sections including a pair of insulatingly spaced concentric conductors, another of said sections including a pair of insulatingly spaced concentric conductors 'electrically connected with said first mentioned bf thecomprising in combination a plurality of relatively movable sections, one of said sections including apair of insulatngly spaced concentric conductors, another of said sections including a pair of insulatingly spaced concentric conductors electrically connected with said first mentioned pair, a pair of concentric relatively movable sleeves provided with complementary conical bearing surfaces secured to the outer conductors of the respective conductor pairs, and a convoluted resilient member associated with said sleeves, the said member being operative to maintain the conical bearing surfaces of the sleeves in wedging fluidtight engagement.

8. A sectionalized coaxial transmission line comprising in combination a plurality of rela-l tively movable sections, one of said sections including a pair of insulatingly spaced concentric conductors, another of said sections including a pair of insulatingly spaced concentric conductors electrically connected with said first mentioned pair, a pair of concentric relatively movable sleeves provided with complementary conical bearing surfaces, one of said sleeves being secured to the outer conductor of one of the conductor pairs and extending therefrom to slidably engage the juxtaposed end of the other outer conductor of the other conductor pair and the remaining sleeve being removably secured to the last mentioned outer conductor of the other conductor pair, and a convoluted resilient member disposed intermediate said sleeves, the said member being operative to maintain the conical bearing surfaces of the sleeves in wedging fluidtight engagement.

9. A sectionalized coaxial transmission line comprising in combination a plurality of relatively movable sections, one of said sections lncluding a pair of insulatingly spaced concentric conductors, another of said sections including a pair of insulatingly spaced concentric conductors electrically connected with said first mentioned pair, a gas under pressure between the inner and outer conductors of the conductor pairs, and a pair of concentric relatively movable sleeves provided with complementary conical bearing surfaces secured to the outer conductors of the respective conductor pairs, the conical bearing surfaces of the sleeves being maintained in wedging duid-tight engagement by the pressure of the confined gas.

10. A sectionalized coaxial transmission line comprising in combination a plurality of relatively rotatable sections, one of said sections including a pair of insulatingly spaced concentric conductors, another of said sections including a pair of insulatingly spaced concentric conductors electrically continuous with said rst mentioned pair, a pair of concentric relatively rotatable sleeves secured to the outer conductors of the respective conductor pairs and a member disposed intermediate said sleeves and in sealing engagement therewith.

11. A sectionalized coaxial transmission line comprising in combination a plurality of relatively movable sections, one of said sections including a pair of insulatingly spaced concentric conductors, another of said sections including a pair of insulatingly spaced concentric conductors electrically continuous with said rst mentioned pair, a pair of superposed concentric relatively movable sleeves secured to the outer conductors of the respective conductor pairs, a flexible cylindrical member provided with a flange disposed intermediate said sleeves, the flange of said member being in fluid-tight engagement with one of said sleeves and the flexible cylindrical wall thereof being in fluid-tight engagement with the other of said sleeves, whereby to eifectizally seal one transmission line section to another. 4

12. A sectionalized coaxial transmission line comprising in combination a plurality of relatively movable sections, one of said sections including a pair of insulatingly spaced concentric conductors, another of said sections including a pair of insulatingly spaced concentric conductors electrically continuous with said first mentioned pair, a gas under pressure between the inner and outer conductors of -the conductor pairs, a pair of superposed concentric relatively movable sleeves secured to the outer conductors of the respective conductor pairs, a flexible cylindrical member provided with a flange disposed intermediate said sleeves, a convoluted resilient member likewise disposed intermediate said sleeves and exerting a force against the flange of the cylindrical member, the flange of the cylindrical member being thereby held in fluid-tight engagement with one of said sleeves and the flexible cylindrical wall thereof being held in fluid-tight engagement with the other of said sleeves by the pressure of the aforesaid gas. whereby to effectually seal one transmission line section to another.

13. A sectionalized coaxial transmission line comprising in combination a plurality of relatively rotatable sections, one of said sections including a pair of insulatingly spaced concentric conductors. another of said sections including a pair of insulatingly spaced concentric conductors electrically continuous with said first mentioned pair, and means for sealing one relatively rotatable transmission line section to another.

14. A sectionalized coaxial transmission line comprising in combination a plurality of relatively movable sections, one of said sections including a pair of insulatingly spaced concentric conductors, another of said sections including a pair of insulatingly spaced concentric conductors electrically continuous with said first mentioned pair, a gas under pressure between the inner and outer conductors of the conductor pairs, and means for sealing one transmission line section to another, said means including a pair of concentric relatively movable sleeves secured to the outer conductors of the respective conductor pairs and held in fluid-tight relation by the pressure of the confined gas.

HUGH E. REPPERT. 

